Microencapsulation simple coacervation

Simple coacervation of cellulose derivatives has been used for microencapsulation of various drugs, such as theophylline, ibuprofen, indomethacin, adryamicin, " and nicardipine. The goal of micro-encapsulating these drugs was to decrease their gastric irritation, mask the bitter taste and, very importantly, to achieve sustained release. 

Nevertheless we have chosen an alternative approach microencapsulation using synthetic polyacrylates which may be stronger and more biocompatible (or at least have a more reproducible biocompatibility). Most of the effort has been with a particular water insoluble synthetic copolymer (HEMA-MMA), although other polyacrylates (water soluble or insoluble) have been used. In general, two approaches have been used complex coacervation with water soluble polycations and polyanions to generate an insoluble complex and simple coacervation with a water insoluble polymer precipitated from an organic solvent. 

Siddiqui, O. and H. Taylor, Physical factors affecting microencapsulation by simple coacervation of gelatin. J. Pharm. Pharmacol., 35(2) (1983) 70-73. 

Mauguet, M.C., Legrand, J., Brujes, L., Camelle, G., Larre, C., Popineau, Y., 2002. Gliadin matrices for microencapsulation processes by simple coacervation method. J. Microencapsul. 19(3), 377-384. 

Complex coacervation is similar to simple coacervation where another complimentary polyelectrolyte is used. Gelatin and gum arabic is a well-estabHshed system for microencapsulation by complex coacervation. Mayya et al. have reported a two-layer encapsulation of paraffin oil, based on a primary layer of interface active polyelectrolyte-surfactant complex, followed by a second layer of the conjugate polyelectrolyte-polyelectrolyte complex [41]. The procedure involves the dispersion of paraffin oil in 1% gelatin solution (pH adjusted to 6.5) containing SDS having concentration less than its CMC, followed by drop-wise addition of the solution of the other polyelectrolyte (1% gum arabic) into the dispersion. The pH is then ad-... 

The coacervation method is one of the earliest microencapsulation techniques, which has been used for various consumer products. This method is based on separation of a solution of hydrophilic polymer(s) into two phases, which are small droplets of a dense polymer-rich phase and a dilute liquid phase. Coacervation can be divided into simple and complex coacervation depending on the number of polymers that are involved in the formation of microparticles. 

Okada, J., A. Kusai, and S. Ueda, Factors affecting microencapsulability in simple gelatin coacervation method. J. Microencapsul., 2(3) (1985) 163-173. 

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